Search results for "Multiferroics"
showing 10 items of 45 documents
Large modulation of perpendicular magnetic anisotropy in a BiFeO3/Al2O3/Pt/Co/Pt multiferroic heterostructure via spontaneous polarizations
2018
Magnetism control has a variety of applications in magnetic storage and spintronic devices. Instead of the control of direct magnetoelectric coupling via strain, voltage, and Dzyaloshinskii-Moriya interaction, the polarization-dependent coupling in multiferroic materials such as BiFeO3 is employed for the electric-field control of magnetizations in this work. A perpendicular magnetic anisotropy (PMA) has been realized in a BiFeO3/Al2O3/Pt/Co/Pt multiferroic structure at room temperature. Interestingly, a distinct change of coercivity field (∼400%) has been observed in the structure with opposite polarization directions, which can be attributed to the different oxidation degree at the Pt/Co …
Strain-mediated electric-field control of exchange bias in a Co90Fe10/BiFeO3/SrRuO3/PMN-PT heterostructure.
2015
AbstractThe electric-field (E-field) controlled exchange bias (EB) in a Co90Fe10/BiFeO3 (BFO)/SrRuO3/PMN-PT heterostructure has been investigated under different tensile strain states. The in-plane tensile strain of the BFO film is changed from +0.52% to +0.43% as a result of external E-field applied to the PMN-PT substrate. An obvious change of EB by the control of non-volatile strain has been observed. A magnetization reversal driven by E-field has been observed in the absence of magnetic field. Our results indicate that a reversible non-volatile E-field control of a ferromagnetic layer through strain modulated multiferroic BFO could be achieved at room temperature.
Magnetoelectric coupling driven by inverse magnetostriction in multiferroic BiMn3Mn4O12
2013
By means of neutron powder diffraction, we investigated the effect of the polar Bi$^{3+}$ ion on the magnetic ordering of the Mn$^{3+}$ ions in BiMn$_3$Mn$_4$O$_{12}$, the counterpart with \textit{quadruple} perovskite structure of the \textit{simple} perovskite BiMnO$_3$. The data are consistent with a \textit{noncentrosymmetric} spacegroup $Im$ which contrasts the \textit{centrosymmetric} one $I2/m$ previously reported for the isovalent and isomorphic compound LaMn$_3$Mn$_4$O$_{12}$, which gives evidence of a Bi$^{3+}$-induced polarization of the lattice. At low temperature, the two Mn$^{3+}$ sublattices of the $A'$ and $B$ sites order antiferromagnetically (AFM) in an independent manner …
The Role of Order-Disorder Transitions in the Quest for Molecular Multiferroics: Structural and Magnetic Neutron Studies of a Mixed Valence Iron (II)…
2012
Neutron diffraction studies have been carried out to shed light on the unprecedented order-disorder phase transition (ca. 155 K) observed in the mixed-valence iron(II)-iron(III) formate framework compound [NH 2(CH3)2]n[FeIIIFe II(HCOO)6]n. The crystal structure at 220 K was first determined from Laue diffraction data, then a second refinement at 175 K and the crystal structure determination in the low temperature phase at 45 K were done with data from the monochromatic high resolution single crystal diffractometer D19. The 45 K nuclear structure reveals that the phase transition is associated with the order-disorder of the dimethylammonium counterion that is weakly anchored in the cavities …
Room-temperature paramagnetoelectric effect in magnetoelectric multiferroics Pb(Fe1/2Nb1/2)O3 and its solid solution with PbTiO3
2015
We have observed the magnetoelectric (ME) response at room temperature and above in high-resistive ceramics made of multiferroic Pb(Fe1/2Nb1/2)O3 (PFN) and PFN-based solid solution 0.91PFN-0.09PbTiO3 (PFN-PT). The value of the paramagnetoelectric (PME) coefficient shows a pronounced maximum near the ferroelectric-to-paraelectric phase transition temperature, T C, and then decreases sharply to zero for T > T C. The maximal PME coefficient in PFN is about 4 × 10−18 s/A. The theoretical description of the PME effect, within the framework of a Landau theory of phase transitions allowing for realistic temperature dependences of spontaneous polarization, dielectric and magnetic susceptibilities, …
Structural transitions under high-pressure in a langasite-type multiferroic Ba3TaFe3Si2O14
2015
Abstract The iron containing langasite family compound Ba3Ta57Fe3Si2O14 was studied at high pressure up to 30 GPa at room temperature by means of in situ X-ray diffraction, Raman and Mossbauer spectroscopies in diamond anvil cell. Two structural transitions at pressures ∼5 and ∼20 GPa are observed. At ∼5 GPa, the low-pressure trigonal P321 phase undergoes phase transition to the most likely P3 structure as manifested by slight increase in the c/a ratio and by anomalies of the Mossbauer and Raman spectra parameters. At ∼20 GPa, the first order phase transition to monoclinic structure occurred with a drop of unit cell volume by 9%. The appearance of the ferroelectric state at such transitions…
Structural, magnetic, dielectric and mechanical properties of (Ba,Sr)MnO3 ceramics
2017
The authors acknowledge the CPU time allocation at Academic Computer Centre CYFRONET AGH in Cracow. This work was supported in part by PL-Grid Infrastructure and the European Regional Development Fund under the Infrastructure and Environment Programme [grant number UDA-POIS.13.01-023/09-00]. The research was partially carried out with the equipment purchased thanks to the financial support of the European Regional Development Fund in the framework of the Polish Innovation Economy Operational Program (contract no. POIG.02.01.00-12-023/08). L. Vasylechko acknowledges partial support of the Ukrainian Ministry of Education and Sciences under the Projects ?RZE?, ?KMON?, and ICDD Grant-in-Aid pro…
Investigations of Low Temperature Phase Transitions in BiFeO3Ceramic by Infrared Spectroscopy
2011
In this paper, results of new infrared FIR-MIR measurements (wavenumber range of 4000–100 cm−1) in the range of the temperature 300 ÷ 8 K of the BiFeO3 ceramic are presented. Below 200 K only one symmetric band at ca. 800 cm−1 is visible. The full width at half maximum of this band decreases exponentially on cooling. The shape of the band at ca. 545 cm−1connected with A1 (TO) mode also changes between 60–40 K, this is in the vicinity of the phase transition at 50 K. Initially a broad band reveals its components as shoulder bands. Theirs FWHM decrease with cooling.
Comparative studies of ferroelectric and magnetic phase transitions in Pb(Fe1/2Nb1/2)O3-PbMO3 (M-Ti, Zr) multiferroic solid solutions
2015
Some peculiar features of magnetic x,T-phase diagram of (1-x)PbFe1/2Nb1/2O3- xPbTiO3 system at x ≈ 0.1 have been ascribed previously to the change of the lattice symmetry from rhombohedral to tetragonal or to the decrease of the lattice parameter with x. We carried out structural, dielectric, magnetization, and Mossbauer studies of (1-x)PbFe1/2Nb1/2O3-xPbZrO3 system, where the symmetry remains rhombohedral, while the lattice parameter increases with x. However, the magnetic x,T-phase diagram of (1-x)PbFe1/2Nb1/2O3-xPbZrO3 appeared to be very similar to that of (1-x) PbFe1/2Nb1/2O3-xPbTiO3. Anomalies of composition dependence of magnetic phase transition temperatures at x ≈ 0.1 are supposed …
Direct observation of temperature dependent magnetic domain structure of the multiferroic La0.66Sr0.34MnO3/BiFeO3 bilayer system by x-ray linear dich…
2014
Low-thickness La0.66Sr0.34MnO3 (LSMO)/BiFeO3 (BFO) thin film samples deposited on SrTiO3 were imaged by high resolution x-ray microscopy at different temperatures. The ultra-thin thickness of the top layer allows to image both the ferromagnetic domain structure of LSMO and the multiferroic domain structure of the buried BFO layer, opening a path to a direct observation of coupling at the interface on a microscopic level. By comparing the domain size and structure of the BFO and LSMO, we observed that, in contrast to LSMO single layers, LSMO/BFO multilayers show a strong temperature dependence of the ferromagnetic domain structure of the LSMO. Particularly, at 40 K, a similar domain size for…